Dualex: a new instrument for field measurements of epidermal ultraviolet absorbance by chlorophyll fluorescence

Goulas, Y.; Cerović, Zoran G.; Cartelat, A.; Moya, I.

doi:10.1364/ao.43.004488

Cited by 213 publications

(150 citation statements)

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“…Para isso, emite um feixe de luz de comprimento de onda a 375 nm (absorvido pelos polifenóis) e outro de referência a 650 nm (região do vermelho), que penetra na epiderme da folha (Goulas et al, 2004;Cartelat et al, 2005). Os feixes de raios UV não absorvidos pelos polifenóis excitam a clorofila no mesófilo foliar.…”

Section: Introductionunclassified

“…Assim, a fluorescência emitida pela clorofila sob esta dupla excitação é proporcional à absorção de UV pela epiderme da folha, o que fornece indiretamente a concentração de polifenóis. Como a maioria dos compostos fenólicos está presente na epiderme, essa medida pode ser utilizada para estimar o teor de polifenóis global da folha (Goulas et al, 2004). O aparelho fornece no visor, em uma única medição na folha, o índice de clorofila (ICHL), o índice de flavonóis (IFLV) e o índice de balanço de nitrogênio (IBN), obtido pela relação entre ICHL e IFLV.…”

Section: Introductionunclassified

“…Neste caso, a determinação desta variável é feita de maneira destrutiva e pouco aplicável na agricultura de precisão. Alternativamente, podem ser utilizadas medidas não destrutivas, como o uso do teor de polifenóis, também relacionado ao peso específico da folha (Goulas et al, 2004 O solo da área experimental foi classificado como Argissolo Vermelho-Amarelo câmbico (Santos et al, 2006). A análise, para a caracterização físico-química do solo, na camada de 0-20 cm, indicou: pH em água de 6,3; 1,4 dag kg -1 de matéria orgânica; 4,4 mg dm de sulfato de zinco, 10 kg ha -1 de sulfato de cobre e 0,5 kg ha -1 de molibdato de sódio.…”

Section: Introductionunclassified

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Avaliação do estado nutricional do nitrogênio em batateira por meio de polifenóis e clorofila na folha

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Finger

et al. 2012

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi avaliar o efeito de doses de N sobre índices fisiológicos relacionados à nutrição nitrogenada e verificar a possibilidade de estimar indiretamente os teores foliares de N em batata. Foram avaliados os índices de flavonóis (IFLV), de clorofila (ICHL) e de balanço de N (IBN), e as estimativas dos teores foliares de N foram realizadas aos 21 e 42 dias após a emergência, por meio do medidor portátil Dualex. O experimento foi conduzido de novembro de 2010 a fevereiro de 2011, em delineamento de blocos ao acaso, e os tratamentos consistiram de cinco doses de N (0, 50, 100, 200 e 300 kg ha -1 de N, na forma de ureia) aplicadas em pré-plantio, com quatro repetições. Houve aumento no ICHL e no IBN e decréscimo no IFLV com o aumento das doses de N. Os índices determinados com o medidor Dualex correlacionaram-se com os teores de N e de clorofila extraível na quarta folha, bem como com o rendimento de tubérculos na safra. O Dualex pode ser utilizado para avaliar o estado nutricional de N em batateira e prognosticar a produtividade de tubérculos.Termos para indexação: Solanum tuberosum, avaliação em tempo real, balanço nutricional, clorofila, compostos fenólicos, flavonóis. Evaluation of potato nitrogen status based on polyphenol and chlorophyll leaf contentAbstract -The objective of this work was to evaluate the effect of N rates on physiological indexes related to nitrogen nutrition in potato, and to verify the possibility of indirectly estimating leaf N contents. Flavonol (FLVI), chlorophyll (CHLI), and the nitrogen balance (NBI) indexes were evaluated, and estimations of leaf N contents were made at 21 and 42 days after emergence using the Dualex leaf-clip instrument. The experiment was carried out from November 2010 to February 2011, in a randomized complete block design, with five N rates (0, 50, 100, 200, and 300 kg ha -1 of N, applied as urea) at pre-planting, and four replicates. There was an increase in CHLI and NBI and a decrease in FLVI with the increasing N doses. The indexes determined with Dualex were correlated with N and extractable chlorophyll content in the fourth leaf and with potato tuber yields. Dualex can be used to evaluate N nutritional status in potato plants, and for the prognosis of final tuber yield with readings.

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Section: Introductionunclassified

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Avaliação do estado nutricional do nitrogênio em batateira por meio de polifenóis e clorofila na folha

Coelho

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Finger

et al. 2012

Pesq. agropec. bras.

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“…A new promising instrument is the Dualex Scientific+ ® (FORCE-A, Paris, France). The Dualex ® can provide four different indices related to the concentration of chlorophyll, flavonols, anthocyanins and N derived by the nitrogen balance index (NBI ® ); it can be used to assess the nutritional status of the crop and the presence of stress [108]. The Dualex ® has been used successfully by Tremblay and colleagues [109], for N fertilization of winter vegetable crops in the open field.…”

Section: Plant Monitoringmentioning

confidence: 99%

New Trends in the Fertigation Management of Irrigated Vegetable Crops

2017

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Abstract:The use of fertigation, coupled with micro-irrigation, has continued to increase since it was first introduced in horticultural cropping systems. This combination provides a technical solution whereby nutrients and water can be supplied to the crop with high precision in terms of time and space, thereby allowing high nutrient use efficiency. However, the correct estimation of crop nutrient and water needs is fundamental to obtaining precise plant nutrition and high nutrient use efficiency in fertigated cropping systems. This paper illustrates the state-of-the-art and new perspectives for optimal nutrient management of vegetable crops cultivated under fertigation regimes. An overall description is reported for the most valuable technologies and techniques based on simulation models, soil testing, plant testing, and related decision support systems that can be adopted for efficient fertigation. However, it should be highlighted that only a few of the above technologies and techniques are practically available and/or easy to use by growers. Therefore, much more attention should be paid in the future to the transfer of research knowledge to farmers and technical advisors.

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“…The feedback mechanism reacts to the fluorescence changes of the sample and adjusts the laser power individually to the sample. Another feedback regulation adjusting the intensity of the excitation light in order to keep the Chl fluorescence stable is used by an instrument with a dual wavelength excitation (DUALEX) 11 . This technique is developed to acquire rapid information about the absorption characteristic of the leaf tissue and thus is used to 'fully eliminate any artifacts caused by variable Chl fluorescence' as has been demonstrated for quality assessment in grape vine production 12 .…”

Section: Fluorescence Parametermentioning

confidence: 99%

Demonstration of plant fluorescence by imaging technique and Intelligent FluoroSensor

et al. 2015

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Photosynthesis is a process that converts carbon-dioxide into organic compounds, especially into sugars, using the energy of sunlight. The absorbed light energy is used mainly for photosynthesis initiated at the reaction centers of chlorophyll-protein complexes, but part of it is lost as heat and chlorophyll fluorescence. Therefore, the measurement of the latter can be used to estimate the photosynthetic activity. The basic method, when illuminating intact leaves with strong light after a dark adaptation of at least 20 minutes resulting in a transient change of fluorescence emission of the fluorophore chlorophyll-a called 'Kautsky effect', is demonstrated by an imaging setup. The experimental kit includes a high radiant blue LED and a CCD camera (or a human eye) equipped with a red transmittance filter to detect the changing fluorescence radiation. However, for the measurement of several fluorescence parameters, describing the plant physiological processes in detail, the variation of several excitation light sources and an adequate detection method are needed. Several fluorescence induction protocols (e.g. traditional Kautsky, pulse amplitude modulated and excitation kinetic), are realized in the Intelligent FluoroSensor instrument. Using it, students are able to measure different plant fluorescence induction curves, quantitatively determine characteristic parameters and qualitatively interpret the measured signals.

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Dualex: a new instrument for field measurements of epidermal ultraviolet absorbance by chlorophyll fluorescence

Cited by 213 publications

References 18 publications

Avaliação do estado nutricional do nitrogênio em batateira por meio de polifenóis e clorofila na folha

Avaliação do estado nutricional do nitrogênio em batateira por meio de polifenóis e clorofila na folha

New Trends in the Fertigation Management of Irrigated Vegetable Crops

Demonstration of plant fluorescence by imaging technique and Intelligent FluoroSensor

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